Process for the production of sensitive films for photographic purposes



i Patented Apr. 24, 1 923.

'- entree s'rarss PATENT cFF J'AQUTES EDWIN BRANDENBERGER, OF PARIS, FRAfiCE, .ASSIGNOR T LA SOCIETE LA t QELLOPHANE. 0F PARIS, FRANCE.

PROCESS FORTHE PRODUCTION OF SENSITIVE FILMS FOR ,I'HOTOGBAPHIC PURPOSES.

No Drawing.

T 0 all whomit may concem:

Be it known that I, Jxorrs Eowm BRAN- DENBERGER, citizen of the Republic of Switzerland, and resident of Paris, F ran'ce, 5 (post-office'address 16 Rue du Louvre)", have invented anew andruseful Process for the Production of Sensitive Films for Photographic Purposes, which improvements are fully set forth in the following specification. This invention relates to a process for the production of sensitive films for photographic purposes.

' It is well known that in order to sensitize for photographic purposes films which do not resist water, especially certain cellulose films, for example the cellulosic films obtained by recovering cellulose from an aqueous solution of soduim cellulo-xanthate, use has been made of an aqueous solution as a 20 preliminary bath with the object of causing the film to swell, and of enabling the substances, which have to. react, to penetrate into the'interior of said film.

The object of the present invention is a 2 process based on the treatment of the film in a preliminary bath 'of pure water or of an aqueous solution of one of the salts required for the treatment, said process being characterized by the establishment of certain abso- 0 lutely definite relations between the baths used. ln order to morei precisely explain the characteristics of the invention it"may be assumed that the process is to be applied to the as by means of silver bromide. owever, it should be well understood that this is only one example of the practical application ot' the process, and that the process can be applied to the production within the interior of the cellulosic film, of any other insoluble salt which is sensitive to light.

' In order to produce the silver bromide two baths are used: one of silver nitrate, and the other of potassium bromide, for example. To produce sensitive silver bromide ,within the interior of the cellulosic film in an absolutely satisfactory manner under these conditions, it is necessary that the concentration of the precipitating bath should be molecularly equal to, or higher than the concentration of the solution which impregnates the film after leaving the first bath. Proceeding in this manner, and taking care to drain off the excess of the first bath, a deproduction of a sensitized photgiaphic film Application filed March 7, 1921. Serial Ii l'o. 450,398.

solution, the potassium bromide bath employed for producing the silver bromide should contain in 100 cc:

at least, of potassium bromide the molecular weight of which is 119, that of silver nitrate being 170. On the other hand, if the first bath consisted of an aqueous solution of potassium bromide containing 7 grams per 100 co, the second precipitating bath of silver nitrate should contain at least 10-grams of silver nitrate per 100 cc.

As mentioned above, the process is genoral, and can be employed whatever the bath used for producing the salt sensitive to the light.

This process gives analogous results to those furnished by fine-grain emulsions of silver salts in gelatine When developed with hydroquinone. As a matter of fact it is known-that, by varying the time of exposure, the dilution of the developer and the time of devlopment, paper or plates coated, for example with finely divided silver-gelatine chloride will give a warm tone such as olive green, sepia, reddish, warm black and the like, or cold tones passing into the blue or violet. 95

By varying the same conditions the aforesaid factors: time of exposure, dilution of the developer, time of development and the like; cellulosic films which have been sensi-' tized by pure or mixed silver halogen salts of very fine grain, will give the same results as regards warm and cold tones provided the films which do not resist water have a very fine grain obtained without ripening or by only carrying said ripening to a certain stage.-

In other cases the sensitiveness this obtained is not sufiicient. It is therefore nec essary to use a ripening process well known in connection with the above specified prod- 10 X 7 grams,

ucts which might'be termed cellulo-chlorides or cellulo-bromides or celluloiodides, by analogy with the terms used in the gelatine process.

By way of example. some methods of ripening, that is to say, increasing the sensitiveness of silver salts on development may be indicated which maybe employed in the process in which cellulose plays the role of a sensitizer.

It may be remarked in the first place that, if the cellulose impregnated with silver nitrate in a cold aqueous solution is immersed for merely a few seconds in a weak solution of potassium bromide, a silver bromide of very fine grain is obtained which constitutes an unripened salt which is generally insufficiently sensitive for the usual application of photography (with the exception however of colour photography by the interferential method of Lipman).

The sensitiveness ofthese silver cellulosalts is increased:

By usingall other conditions of tim and temperature being equal-more concentrated solutions of either the silver salts or halogen salts or both;

By carrying out the operation at higher temperatures By prolonging the-time of the action of the precipitating bath, either cold or hot, acting in this case, either on a large quantity of the bath, or simply on the small quantity retained by the cellulose by simple impregnation; v

By impregnating the cellulo-salt already formed with a suitable solution which may inter alia be a solvent of the cellulo-salt, and by taking precautions in this case to pre-saturate this solvent with the same silv'er salt with the object'of preventing the salt formed in the cellulose from being dissolved;

By adding suitable substances to one or to both baths. In this way the sensitiveness is increased by working with iodized silver nitrate or by adding ammonia to the solu'- tion of the halogen salts;

By combining the halogenated salts in suitable proportions so as to produce for example an iodo-bromid'e of silver.

Vhat I claim and desire to secure by Letters Patent isz- 1. The process for producing a sensitive film for photographic purposes, which consists in treating the film successively with two liquids, the first liquid consisting of an aqueous solution of one of the substances which is intended to enter into reaction with a substance contained in the second liquid, said second liquid containing a percentage of the said substance at least equal to the chemically equivalent percentage of the substance present in the first liquid.

2. The process for producing a sensitive film for photographic purposes, which consists in treating the film successively with two liquids, one liquid consisting of an aqueous solution of a silver compound intended to enter into reaction with a halogen compound contained in the other liquid. said other liquid containing a percentage of halogen at least equal to the chemically equivalent percentage .of silver of the first named liquid.

3. The process for producing a water permeable sensitive film-for photographic purposes, which consists in providing said film with an insoluble silver compound of very fine grain in such way that warm or cold tones are obtained in developing the picture produced on said film, by treating the filmsuccessively with two liquids, one liquid consisting of an aqueous solution of a silver compound intended to enter into reaction with a halogen compound contained in the other liquid, said other liquid containing a percentage of halogen superior to the chemically equivalent percentage of silver of the first named liqui 4. The process for producing a photographic film with increased sensitiveness, for

positive and negative photographic purposes,

consisting in sensitizing a cellulosic film with a silver halogen compound, by successively impregnatingthc film with two liquids, one of which comprises a silver compound, and the other a halogen compound in such way that one of said liquids acts as a precipitant I for the other, and causing a ripening of said sensitized film by adding suitable substances to one "of said liquids.

5. A film for photographic purposes, com prising a cellulosic support recovered from a cellulose solution, said support containing sensitive salts in its interior.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

JAQUES EDWIN BRANDENBERGER. Witnesses:

Gnoaons GA'soAL CARRmnn, GERMAINE MroHIn s,

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